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Mosses, Mites and Mating

Everyone knows how pollen gets from plant to plant: by the work of insects or the wind, generally. But how about plants like mosses and other bryophytes that don’t have pollen, but sperm?

Scientists have long assumed that, like human or other animal sperm, moss sperm have to get around under their own power, and that they need wet conditions to swim from one plant to another. (Like human sperm, they have flagella for the purpose.)

“There have been suspicions for a long time that this is not the whole truth,” said Nils Cronberg, a professor at Lund University in Sweden. There have been cases of moss fertilization, he said, that were difficult to explain by swimming.

Scientists suspected that, as with pollination, insects or other organisms might also be involved. “But nobody ever tried to do a test to see whether animals could really do this,” Dr. Cronberg said.

Now he and two colleagues, Rayna Natcheva and Katarina Hedlund, have done just that. Their conclusion: mites and springtails can carry sperm between moss plants.

Their experiments, described in the journal Science, were very simple. They used a common moss — a kind that grows between paving stones — and placed male and female plants various distances apart in laboratory dishes. The bottoms of the dishes contained plaster, which absorbs water. So while the moss plants could be kept moist, there was no water allowing sperm to travel between plants.

They introduced mites or springtails (creatures commonly found among this type of moss) to some of the dishes. Fertilization occurred only in those dishes, no matter how great the separation.

The researchers also wanted to know whether sperm carrying was an active behavior as pollination is with bees, which search out pollen-bearing flowers. In another set of experiments, they found that the mites and springtails actively sought out fertile moss shoots and ignored sterile ones.

Dr. Cronberg says that sperm carrying may be widespread in mosses and other bryophytes, and that it has probably occurred for far longer than pollination in angiosperms, the flowering plants.

Bryophytes, mites and springtails “are evolutionarily very old,” he said, adding, “They’ve certainly been around a lot longer than angiosperms and most of the insect groups which are pollinating.”

Avoiding Premature Breakdown

You may not have noticed, but there’s been a revolution of sorts going on in your washing machine over the past several decades. Laundry detergents now include enzymes — often bioengineered ones — that break down proteins, starches, cellulose and other components of fabric stains.

But keeping enzymes stable is a tricky business. For one thing, enzymes are proteins themselves, so a protein-destroying enzyme can destroy other enzymes in the detergent before they get a chance to work in the washer. Other chemicals in detergent can harm the enzymes as well.

Photo

Credit
Chris Gash

Scientists at Southern Illinois University have come up with a way to protect stain-fighting enzymes in storage. Their technique encapsulates the enzymes in a protective gel. When the gel is put in wash water it dissolves easily, releasing the enzyme.

Kiranmayi Deshpande and Bakul C. Dave of Southern Illinois, along with Mark S. Gebert of Genencor, a major developer of detergent enzymes, used a sol-gel process in their research. In a sol-gel, silica particles in suspension (a colloid) are gelled to form a solid. In the gelling, other molecules can be enclosed in the solid matrix.

Sol-gel encapsulation of molecules is not new. But figuring out how the molecules can be released in a controlled way has been a stumbling block. The researchers used amino groups — one nitrogen atom with two hydrogen atoms — to make the resulting gels water soluble.

They found that the enzymes retained their effectiveness for long periods of time when encapsulated. But once mixed with water, they were quickly released. The findings are being published this month in the journal Chemistry of Materials.

Since 1931, a research project known as the continuous plankton recorder has been sampling the North Atlantic. The project uses special devices that are towed behind merchant ships on regular routes, picking up and preserving plankton on a band of gauze — a continuous record of the tiny organisms.

Since 2002, the recorder has picked up something else in the northeastern part of its run — unusually high counts of larval and juvenile snake pipefish. Richard R. Kirby of the University of Plymouth in England and colleagues have now correlated the increase in pipefish numbers to a rise in sea-surface temperatures, a result of global warming.

Snake pipefish are a large, thin and exceptionally bony fish found in deep waters from Iceland to the Azores. They are relatively unusual in that, like seahorses, the males care for the eggs, which they keep on the underside of their body.

Warmer ocean temperatures can increase the survival of young fish because they speed up growth during the larval stage, when the fish is extremely vulnerable to predation. The researchers say that faster larval growth is probably contributing to the rise in pipefish numbers.

But there may be something more unusual at work, they report in the journal Biology Letters. Warmer ocean temperatures may be affecting sex role dynamics.

When the males are caring for the eggs, they are unavailable for mating. This effectively limits reproduction rates, since females must compete for the available males. But with warmer temperatures the eggs develop faster, and the males become available sooner. More females can find mates, and reproduction increases.

Help for Hedgehogs

Hedgehog lovers in Britain have scored a victory in a long campaign to protect the animals from one unintended consequence of fast food. The McDonald’s Corporation in Britain began distributing a redesigned lid for its McFlurry dessert cup so it would no longer be a potential death trap.

The previous lid had a large opening for adding and stirring candy pieces into the soft-serve mix. Unfortunately, the opening was just the right size for a hedgehog to climb in. The animals often got stuck inside.

A smaller opening in the new lid should keep hedgehogs out of any discarded McFlurry cups.